Taconite Inlet Project

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Map of Lake C2 showing the coring locations and the bathymetry of the lake.

(image of coring)

Green dots mark the short core transect, red dots the transect of longer cores through the oxycline of Lake C2.


Sources of high resolution (i.e. annually resolved) paleoclimate information from the Arctic are currently limited to ice cores. However, annually laminated lake sediments provide another means of reconstructing past climatic variations in the Arctic. Lake C2, like most lakes at high latitudes, is frozen over for 9-10 months of the year and only receives runoff for a brief period in the summer. During this time, sediments are carried from the land and are deposited in the lake; during winter months no runoff occurs and the only sediments transferred to the lake floor are those fine particles left suspended in the lake waters when summer runoff came to an end. These slowly settle out, producing annual laminations (varves) each of which are made up of both coarse and fine sub-layers. Sediment cores retrieved from lake C2 thus contain a record of laminae (analogous to the annual growth increments of trees) which record conditions in the lake watershed year-by-year.

Two sets of sediment cores were recovered (see Figure above):

a) a set of longer cores (~ 1m) along a depth transect which crossed the oxycline in the lake. Because laminated sediments in Lake C2 are only preserved below the oxycline, cores across a depth transect through the oxycline have the potential for documenting changes in the position of the oxycline through time.

b) A set of cores along a transect from the main inlet stream to the lake outlet (see Figure). Detailed studies of short cores along this transect were studied by B. Zolitschka to understand the sediment depositional pattern from proximal to distal locations, with respect to the main delta. In addition, long cores (~2.4m) were recovered from the deep (>80m) basin in the lake. Work on these sediments is currently in progress.

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